The goal of the work is to examine the tense and agreement systems of children with and without specific language impairment (SLI) in Southern African American English (SAAE) and Southern White English (SWE). Although strides have been made in the study of SLI in SAAE and SWE, there remain significant gaps in our knowledge of these dialects, and of the manifestations of SLI within them. These gaps in the literature create barriers to the representation of SAAE- and SWE-speaking children within applied and theoretical research, and this impedes the development of valid and efficient clinical services for children who speak these dialects. The focus of the work is on tense and agreement because recent findings from our lab and others indicate that nonstandard English-speaking children with SLI present difficulties with this aspect of language when compared to same dialect-speaking controls. These findings are consistent with two linguistic theories of SLI, the Extended Optional Infinitive account (EOI; Rice & Wexler, 1996; Rice, Wexler & Cleave, 1995) and the Feature-based Limited Functional Category account (F-LFC; Hegarty, 2005). Within the proposed work, we will further evaluate and specify the nature of the SLI tense and agreement deficit within SAAE and SWE and complete four tests of the EOI and F-LFC models. The four tests involve: 1) the nature of the SLI tense and agreement deficit within SAAE and SWE; 2) the nature of the tense and agreement systems of typically developing children who vary in their nonstandard dialect use; 3) the relation between measures of children's tense and agreement systems and their general language ability, cognition, and environment; and 4) the relation between children's overt marking of tense and agreement and their overt marking of other functional categories (negation, complementizers) within an utterance. For the first three tests, the models make similar predictions but for the fourth, the models make different predictions. To achieve these goals, we will complete one large-scale study of 240 children in eight participant groups. These groups will allow us to compare same-dialect speaking children with and without SLI to each other (Test 1); evaluate differences between groups of typically developing children who produce low, medium, and high densities of SAAE and SWE (Test 2); complete regression analyses (Test 3); and complete a functional category analysis of utterances that contain tense and agreement, negation, and complementizers (Test 4). The data will come from language samples, standardized testing, and experimental probes as has been done in studies of standard English. However, to adequately evaluate the children's language systems and test the predictions of the EOI and F-LFC models within SAAE and SWE, we will create dialect-appropriate stimuli and dialect-appropriate coding systems. Findings from the work will lead to improved clinical services for children and a reduction of the health disparities that exist in the rural Deep South and elsewhere.